Killay South (Welsh: Cilâ - De) was an electoral ward in the City and County of Swansea, Wales. The ward was mainly rural and consisted of some or all of the following areas: Dunvant, Ilston, Killay, Sketty and Upper Killay in the parliamentary constituency of Swansea West.

It was bounded by the wards of Dunvant and Killay North to the north; Sketty to the east; Mayals to the south; and Fairwood to the west.

For the 2012 local council elections, the turnout for Killay south was 43.73%. The results were:

Candidate	Party	Votes	Status
Jeffrey William Jones	Liberal Democrats	429	Liberal Democrats hold
Peter Jones	Labour	327
Graham Coombs	Conservative	111

51°37′06″N 4°01′25″W / 51.61836°N 4.02360°W / 51.61836; -4.02360